Bioactive Starch Foam Composite Enriched With Natural Antioxidants from Spent Coffee Ground and Essential Oil

Starch foam composites containing extracted spent coffee ground and 10 wt% of spent coffee ground (SFE-10) are prepared by compression molding. Four to ten weight percent of oregano essential oil (OEO) is added to the SFE-10. Characterization by ATR-FTIR and total phenolic assay confirms that bioactive compounds of OEO, spent coffee ground (SCG), and extracted spent coffee ground (ex-SCG) penetrate into the samples. The minimum inhibitory concentration against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) is investigated in SFE-10 incorporated 8 wt% OEO. Synergism in antibacterial activity is also achieved from the starch foam incorporated combination of OEO, SCG, and ex-SCG. The kinetics of polyphenol release in food simulants are observed, and the release rate increases when the polarity of aqueous simulants decreased. The water resistance of the samples improves with increasing OEO content, whereas the biodegradability and flexural strength slightly decrease. Based on the results, SFE-10 containing OEO has a good potential for application as a bioactive packaging to preserve and maintain the quality of food.